Didj U-Boot NAND Flashing

This is a tutorial on how to recover your Didj from absolute failure. It will take a Didj whose NAND has been completely erased, and bring it back to fully functional. Though there is one issue, Bad Blocks, which may get in the way of recovery. I don't recommend doing a full erase of your NAND as this will erase the Bad Blocks set by the factory.

TODO: Investigate more about Bad Blocks and how uboot deals with them.

Programs Needed

Hardware Needed

Files Needed

uboot.bin with SD capabilities [1]
lighting-boot.bin (jburks' version 1.4 recommended from above link)
kernel.bin (Either from LFP Package or a known working version)
erootfs.bin (Either from LFP Package or a known working version)

Getting Started

Gather the Files Needed and transfer them to the main directory of the SD Card, they can not be in a folder.

Eject your SD Card and put it into your Didj SD Card adapter.

You are now going to need to load a bootloader over UART Linux/Windows but stop at uboot, also read this tutorial for information on the different bootloader 1.4 variants, you'll need both UART and NAND versions, UART to get started, and NAND to install.

lightning-boot.bin v1.4 should now be on your Didj. Turn it off, and back on, and you should see the blue screen with menu choices come up and we can move on to installing the kernel. If not, double check your numbers, its easy to put in an extra 0 or leave one out.

Kernel

From the bootloader screen, chose Load uboot from SD

Initialize SD capabilities.

LF1000# mmcinit
SD ver 2.0
SD found : Size = 3866624 KBytes

Load kernel.bin into memory at address 0x1400000 and write down how many bytes read.

The length is the hex value of the number you wrote down earlier, in this case 1310720, the easiest way is to open up your calculator into scientific mode, make sure its set to decimal, and enter the number, then switch it over to hex, it'll convert the number automatically.

The length is the hex value of the number you wrote down earlier, in this case 7077888, the easiest way is to open up your calculator into scientific mode, make sure its set to decimal, and enter the number, then switch it over to hex, it'll convert the number automatically.

Watch the terminal window while the Didj boots up. Depending on why your Didj required being recovered, you may get various errors.

If booting fails

A kernel panic means something went wrong with writing the files, make sure you got the addresses correct, and your kernel.bin and erootfs.jffs2 were good working copies, then try again.

If it stops at line "fw= bl= pkg=0" you should have command line access, the next step in booting is the Didj AppManager. I had a problem where the size of erootfs.jffs2 was too short, causing certain programs to not be available, double check your calculations and try again.

Finish Restoring

At this point if everything else went okay, its possible only the /Didj /dev/mtdblock9 USB part is left to be dealt with. Possible issues could be /Didj brazenly refuses to mount because of needs_repair flags, left UNLOCKED because a serial number could not be found, or any number of issues. Best case scenario, plugging in the USB cable starts up LFConnect if you're on Windows, and it fixes the Didj the rest of the way. It may require you needing to create a profile first, in which case you will have to manually fix the Didj the rest of the way.

No Serial Number

From on the didj. Disable and lock mass_storage

# usbctl -d mass_storage -a disable
# usbctl -d mass_storage -a lock

This should make /Didj mount and be accessible from inside the Didj. Open vi with UnitID.txt as the file name

# vi /Didj/UnitID.txt

You'll need to include your Didj's serial number into that file. If you've got previous boot logs, its in there, if you've loaded LFConnect, it created a folder in /All Users/Application Data/Leapfrog/Mnt/<Serial Number> Save the file, and reboot, it should recognize your serial number.

Needs Repair

This will be solved if you can plug into LFConnect, and it is able to sync your Didj. If not, on the Didj